Ossicles appearing in the medial menisci of three patients appeared to be post-traumatic in two and developmental in one. The histologic analysis in the two post-traumatic patients showed relatively normal bone and cartilage, but without the specific structural cartilaginous adaptations found in a naturally occurring large animal model. The third patient, with tibia vara and TAR (thrombocytopenia--absent radius) syndrome, developed the ossicle spontaneously. He is the youngest reported patient, to date, to develop this anatomic variation.